This is the first year of this project and has been taking place while the laboratory was being set up. During this year we have written and had approved the ASP that allows the work to take place. Also, equipment has been set up, and Dr. Pitcher has received training in creating the arthritis model. In the study proposed here, we aim to dissociate the stress-induced effects of the exercise paradigm from the exercise-induced effects. We will do this by comparing an exercise paradigm known to produce stress with a paradigm producing little or no stress, as well as comparison with a sedentary group, all in terms of changes in nociceptive hypersensitivity following experimental mono-arthritis. In addition to employing behavioural and physiological measures of stress, we will standardize the amount of exercise in terms of speed and distance. We will use a common, clinically relevant arthritis model where a small amount of irritant is injected into the ankle, producing arthritis-like symptoms that last for 4-6 weeks. After induction of arthritis, rodents will exercise for 6 weeks. They will be tested for nociceptive hypersensitivity, anxiety-like behavior and for physiological correlates of stress at baseline (i.e. prior to arthritis and exercise), at critical time points during the experiment as well as after the 6 weeks of exercise. Together, this will give us a clear picture of how exercise and stress alter arthritis-induced nociceptive hypersensitivity.